Discussion of Background
A known process for the manufacture of a carrier for label stock is disclosed in German patent 2,212,995. According to this known process, a multi-layer structure incorporating a carrier strip covered on its two faces by adhesive films designed to form labels passes successively through a first printing-and-cutting station enabling labels to be formed on one of the faces. The carrier then passes through a second printing-and-cutting station enabling labels to be made on the other face.
The cutting operation for the adhesive films has to be performed very precisely to avoid damaging the carrier strip, and adjustment of the cutting blades defining the profile of the labels and of the counter-blocks designed to support the pressure of the blades is delicate. In addition, the difficulty of cutting is increased by the presence of the layers of adhesives bonding the films to the carrier strip, the thickness of which can be on the order of 25 to 30% of the total thickness. These layers of adhesive are compressible and pose a risk of flowage. Further, the adhesive thickness is typically known only within wide tolerances, and the thickness of each layer is liable to vary, for example, between 17 and 23 μm during production for a nominal thickness of 20 μm.
Thus, even if care or precautions are taken, there remains a risk that the carrier strip will be cut when the thickness of the adhesive layers is minimal, which in turn creates a risk that the carrier strip will break during the labeling operation in the packaging line.
There is also a risk, when the thickness of the adhesive layers is large, that the outline of the label will be inadequately cut, thereby impeding its subsequent detachment.
In addition, there is a risk that the adhesive will flow on either side of the label and create unwanted areas of adherence during the reeling operation.